video player

To play video on a web page, the FlowPlayer (http://flowplayer.org) works good.
To dynamically change the video, first, a play list could be created:

<a id="player" style="display:block;width:520px;height:330px" ></a>

<script>
var player_obj = flowplayer("player", "flowplayer/flowplayer-3.2.2.swf",
{
clip: {
baseUrl: 'http://host.com/Test/Videos/',
autoPlay : false
},

playlist: [
'clip1.flv',
'clip2.flv',
'clip3.flv',
'clip4.flv'
]
});
</script>


and then select a clip to play by the following command:
player_obj.play(n); // n - the index in the playlist

To convert the video to .flv format this free converter could be used:
http://www.brothersoft.com/cool-mp4-to-flv-converter-229933.html

List of available converters (some paid):
http://www.brothersoft.com/downloads/mp4-to-flv.html